1. Field of the Invention
The invention relates to air damper assemblies particularly for heating, ventilating and air conditioning systems. More particularly, the invention relates to air damper assemblies of the type that have a plurality of damper blades mounted for pivotal movement to regulate the volume of air that can be passed therethrough, or to completely block such air flow.
2. Description of the Related Art
Air damper assemblies including moveable louvers or damper blades for regulating air flow or completely blocking such air flow are well known in the art. Generally, an air damper assembly includes a rectangular frame for mounting of the air damper assembly in a suitable position with respect to the air flow. The frame includes a frame opening defining a flow area through which the air flow passes.
A plurality of damper blades, all of which are typically identical, is disposed horizontally within the frame opening. Each of the plurality of damper blades is generally rectangular in configuration and is rotatably mounted about its longitudinal central axis to the frame. Modulation of the plurality of damper blades determines the flow rate of the air flow by variably restricting the flow area of the frame opening. The flow area is maximized when the damper blades are rotated to an open position, whereat the damper blades are substantially coplanar with the air flow. Contrarily, the flow area is minimized, or even sealed tight, when the damper blades are rotated to a closed position, whereat the damper blades are transverse to the air flow.
Typically, the plurality of damper blades is coupled together and simultaneously actuated by a mechanical linkage. More specifically, a bracket or link is fixedly secured to each of the plurality of damper blades and a rod is pivotally connected to each link. The rod in turn is operatively coupled to an actuator, such as a pneumatic, electric, two-position, modulating, or spring return type actuator. Thus, linear movement of the rod by the actuator actuates the plurality of damper blades between the open and closed positions. Such mechanical linkages are complicated, include multiple connections and joints which leads to looseness or play in the linkage, are prone to failure, and are difficult to service. Consequently, it is desirable to provide an air damper assembly having an improved system for actuating or modulating a plurality of damper blades between open and closed positions.